Level indicator



im so, y1.931.

R. LE sa-myn? 1,811,945 j Lavar, mnrcg'roa 4 Sheets-Spa 1 Filed aune 1:5, 1921V inferpfed by the suie with the V- .mme im se, .seal I @msnm .nm :amt-'mor @strenuamenmrcszron p'picatd'ou filed June 13,

This invention 'relates to level indicators `and its object is the 'provision of a generally improved und simplifed'indicator based;

on 'the different criti-cnlangles of refraction f of different fluids or medio.V and upon the phenomenon of total reflection of parallel' vrays of light when their incident angle is beyond the critical refr-action angle .of thev transparent material on one of the iuids.

A lo The'indicato'r of tlie present invention is 'adapted for use 'as a boiler gauge and has particular utility for indicating two remote positions and at ditcult angles. This is advantageous Where it is desirable to poi lo sit-'ion the gauge relatively hi l1 as n ow com Inonly necessary and it a-voi s the necessi'tv of the attendnts ascending to 'and deseen ingrrom the gauge vevery time that .a read ing is-desired.

" n is n) be understood, howeverf that the .invention is not to be limited-'to any par'- ticular use or purpose but tony be employed' I shall describehthe' indicntor'in comico-- tion-With a. boiler installation but this 4is illustrative andnot lirx'iiting'nnd the iuids may be other thanwater and steam,

According to: the present invention the parallel' rays of' light 'are'd-irected .thru the 3Q transparent material and upon .the 'fluid column at' an en' lebeyond the critical refracf tion angle of t Ie transparent material o'n one' of the .liuids' and within the critical refrac- Y tion .angle oft-he transparent material upon the other Enid. f 4YVhere the rays of light' are intercepted by the 'fluid lwith the' lesser critical angle, total reflection .of the rays' will loccur and Where the rays 4otlightnre Y res-ter 40 rltcic-garl angle they are .reracted thru the ,Y The invention provides .for i-miicaitir.g the f level on the sideof the indicator .opposite .the

position of the source of light by the rs.

. ,s which are retracted thru the Suid withtge 11s-21. `-iseafiel No. 198,630.

tu-red lplates have been required and thev indication has been .dependent .upon the prop- Yer relationship between .the inclined apertures in one. plate with' respect to those in f the other plate.` 'y

The present i'nventionavoids ,this `and even 50j provides for producinv `the indication by the different-.indices o ,-reraction without the second ape'tuxed -orsclector plate hereitofore required;

I also provide for inexperls'yely embody '65 ing the invention in existing i.ndicii-tors,con v j veniently and-with little 'alter-n tioi'l.Y

The invention is.-equally as applicable to tubular indicators and to indicators of y'the t Vlzit plate type and the ind-ieting-side o f the I0A auge maybe provided with asuite-ble difser for inc reasin' or 'widening the field-of:

visibility. The di user plnte may vbe multicolored or otherwise distinctl- 4finished' upon opposite sides of predetermined level to in. 75

`'dica-te according to the obstruct-er of .the -lield y in which the light is'diiused Whether the 'level isabove or 'below the predetermined 1eveL Ta acquaint those skilled nl sie are with auf Athe construction .and operation of several embodiments of the-invention .shell now' y describe sarna in connection with the aci lcorrige:lying AdraWi-n in-vhichz' Fig. l is a vertice fand "more Vor less diaja-mmstic sect-ion --thr'u one cmbodimentof t e invention.'

' Fig. v2 is a horizontal section telt-enen the' line 2:-- 2'of Fig. 1.

Fig., r3 'an'enlarged -frn-gnientnry ltion thi-n the transparent plates shown in Fi 't 1l Y ig. 4' is-a. fragmen'tar section thru an alternative 4arrangamen't or embodying the `showing the man-ner of embodying the nvention in an existing gauge of the type shown in Fig. 5.

u line9-.9 of Figur view showing one `use of the present invenf 32 are reracted at 34 t another embo Y Fig. 15 is a horizontal section taken on the other embodiment.

Fig. 7 "is a. fragmento ver-,tical section thru `another embodiment?y v y' Fig. 8 is a view similar -to Fig. 1, thru `another embodiment. i

Fig. 9 is a. horizontal section .taken on the e 8.' .I h

F ig.- 10 is a fragmentary detail vertical section showingthe embocliment of the few tures of Fig. 8, in en existinggauge.

Fig.- 11 isa section teken on-the line. 11-11 of Fig. 10. v

Fig. 12 is a -fra enta'ry vertical section thru v another embo ent,

,'Fi 13 is a detail horizontal section on .the line 13-13 of Fig. 12. Fig. lll i'se fragmentary vert-'ical section iment.

line 15-15 of Fig. 14.

Fig. lis a diagram indicatingthe man imum eld'hof refraction of less on' steam or air showing a ray of li 't within this einen tion ofthe gauge perse be varied Widelywithin kthe scope of the `present invention.

Where thcindicator is used as av-boiler lgauge the lower frame portion 11 may be provided with a suitable'water connection 416 and the Upper frame portion 10 provided with a suitable steam connection 18. Ob

eatin the level of any other desired 'fluid or media having diierent critical refraction angles. The fiuid 2O may for example be water with the overlyin Huid 21 nir instead of steam. The level o the water or other lower fluid 2O is'indicated at 22 in Fig, 1.

A suitable source of light 24, preferably a relatively high power' bulb although this may vary, is disposed in front of the plate 5 [and suitable means is provided, such as a filter or screen 25 linterposed between the 85 plate 5 and the sourceof light 24.- -for di resting only parallel rays of light upon the plate 5. A parabolic reflector or other suit-4 able means may be employed for directing only parallel llght rays upon the plate 5. 'Where a lter or screen 25 is efm loyed it viously the indicator may be used for indie and t e fluids 20 and` 2l may be any lluids (5 may comprise a. suitable opaque p ate having downwardly inclined relativel *Wide slots 26 extending therethrough and directing the parallel rays of l-ightdownwardly at an angle upon the plate 5. Alternativ'fely the A filter 25 may comprise alternate downwardly inclined llil-Inman of transparent and field and rerajcted on thru t estenngoreiiopeque materiel or it may be otherwise and another ray 'outside-the field of ref-rec formed to direct the rays of light'paral-lel 100 Fig. 1a

isa more or less diagrammatic tion; and

Fig. 19 is a fragments y section of Yal1- Referring to. the drawings, the ,gauge Shown in Figs. 1, 2', and Sis of the plural plete type having a. pair of transparent walls or plates 5 and 6 dening between lthem the' column 8 for the iluidthe level of-whieh is to be ascertained forA indicated'. The trans-4 eolnnm 8 are clcsedby asuitableframe '9 having upper sind lower head portionsl and' 11 mspectively 'and verticel side porthe sections .clamped together' Y with the-glass walls 5 ,end 6 in posit-ion 'by bolts 14. The ofthe fram-e may be gesketed at lend the -Iletaiis of construc- Y with each other and atanangle downwardly upon the plate 5.

As shown -in Fig. 1, end more articularly in Fig. 3, the 'opter surface .o the glass Wall or 1plate 5'is divided into a plurality ofv upward y presented inclined faces-30 parallel with each other and at such tiin-.angle that' the inc-ident parallel 'liglht .rays indicated at ru the plate 5 as indicatednt 34 at an angle between the res. ceti-ve critical refraction' angles of the iilids contained Within -the gauge. The inclination of the oppositely inclined :faces 35 is prcferablysuch as to 1`"-emove these faces from 'interceptng the incident rays 32. They are shown-jas substantially perallel with the incident rays of light. The manner of calculating the critical an le between Aglassend steam orai'r is fo oxvs:

I Inder of refraction 7ciP-1 Critical 'angle sin s' e' 1 4 Befween steam-.and glass, k= 1 .46 I Sin -(critical) =0.6'85 i .Oirleritical angle r 43 Therefore all incident rays of light angles AOB l endB are not-re'-aeted thru the steam 'but are reflected beck thru the glass indicated at XoY.

.For vvatera'nd glass:

' eonutered-and will be refracted Where. Water isencountered.

The faces are as :1l-read pointed out at such en angle that the lig t rays are retracted therein at anv angle between the respective critical refraction an les of the steam and wateror other lui Vs contained with-in the gauge so-thet where steam 21 is encountered the refracted rays 34' 'are reflected et 3-8- hack thru `the `glass whe-reas Where the Water'is encountered the refracted Q rays 34 erefurther refreoted thru the water.

at 40 and thru the glass plate yor Well 6 on the opposite side.-

The opposite or rear side of vthe late 6 has inclined. feces l2 'which' may, or example, be parallel ia-ith the feces 30 and from which vthe lightlrays are directedV at 43 downwardly upon and thru a. Suitable dif- .'user 4 5. The' incline-tion of the Asurfaces '42 lis such that the reys'esn' -emerge from.

. the plete 6 and vto' avoid total reflection of the ,emerging rays beck therethru. The

` idiffuser 45 may consist,- for example; 'of' a 45 lass xereon a p u-rality`o indieations or other irregularities for diusing .the light' plete ioundon one side andheving and the plete 45 is sov dis Athat it will receive the rays refraoted t the water and by its use the-indications furnishedby'.- the iuingrays that refraction' by the Water .can

be observed from a. distent point. The opere-tion of a diuser of thisfsort is well 1in-v de'rstood in the, ert andthe details of the dinser peryse may be varied. The diffuser ma be omitted entirely where desired. The .di oser plete 45 is; by theserays below the uppermost ray which is refg'cted thru 'the Weten depending upon its level and* by the l-e'el ofthe -fvht :on the dinser the level of the-Water int e gagge can be 'ascertained from a. diste-nce and et derent angles. l

For .er1-ample shere the indicator is used es a boiler gauge .and is nfrnifnged atfa com',

paratively greatheight as 'indicated in Fig. '18 yzie is commonly necessary rend ns' indicatedin Fig. 18, the-observer may at muehl'ower 'positlon on the door R ascertain by the level of the light on the diffuser 111.5'V the level of the water within. the gauge. A typical boiler setti-ng' is indicated at 48 end will the diffuser. a lnrger -ield of visibilit] at P may provided or by removing;r the i'ueer .a relatively narrow. field o visibility' may be secured as indicated at P". l

The source of light 9A may he provided I with a suitable hacking or reflector 50 .as

desired. The condition of 'the water level may be readily ascertained from below the gauge and aten 'angle of say 45 and the observer will see acontinuous Streak of light borresp'ondi'ng to the height of the water evel. Y

The 'diiuser plate may bemulticolored or otherwise distinct-ly finished upon opposite -sidesof a Rredeter'mined level to indicate according tothe character ofthe field in which the light is diiused whether the level is above or below the predetermined leveL Additionaltransprent gaskets may, of

course, be added,`to protect the 'reflecting plates :Brom thev undesirable yaction of the Y fluids without meiring the 4opera-tion of the ep aretus. Y

n theembodiment of Fig. 4, I have shown A a. suitable refraetn'g plate 52 for embodyingl i the invention in `a. gauge allel transparent plates.v

The ordinary parallel facedv plate is indicated 'at 5S and the refracting plete of the present Ainvention is secured thereto by a. suitable trenv arent cement binder 53' or otherwise. as This -rovides for inexpensivel'y embodying the .invention in expte-vided with .pari istlng indicators conveniently with little alteration, the inclination of the faces of the transparent plete 52 such that th parallel incident light rays 'are refraete'd therein et an' angle between the res tive critical refraction angles of the dui' con. tained in the gauge'.

In Fig; 5, the transparent plate 6 yis .ont-

ted .and the frame 55 hes an' integral .opaque 1'15 beck 56 closing the back or rear side of the duid column? which ispxovided withsteam Water fcormecsions58-l and 59 tively or other editable `fluid eonneetions.

In lthis ease the trnn'spanent front plate or wall `5 is provided with the inclined feces 30, as before, the angles of which -ar'e such that the incident parallel light rays 32 are re-' -frected therein at im angle between the respective critical efrction angles of the .fluids within vthe f 3nuge.A The source `of lightv .24 is shown 4es disposed 'horizontally with' the filter or -25 positioned to-direct only parallel incident rays u. .on .the trans; v Y parent plate 5.v The source o light 24 may l?? I w .u

.-4 j f* 1,811,946'v l ector 5 0-as before.

In this case, however, indictionis given on theside on .which :the light i-s disposed;

where there is a diffuser it is disposed: at 5S -in `front of o r on the sii-me side of the plate 5 on which the source of light 24 is '-dis posed. Because of their .angle between the respective critical angles of the Water and steam or other fluids the retracted rays 59 are totally reflect-ed at .60 Where thel steam or air is encountered Asind arev refriict-ed at 61 thru the water `Where the'ivater is encountered.v

In this case the continuous streak of light upon the diffuser -58 for indicating the level of the water witliintlie gauge is produced penetrating the water or one of the fluidsby the totally reflected rays 60 instead of by the rays retracted. tlirL the water as before. The inner surface 62 of the rear wall 56 is preferably unp'olislied und of clark color or otherwise finished. so thattlie rays 61 will not be rellected.v Y

In this einbodimentobviously only one transparent plate is required and the matter-v of sealing and the other problems are r'e duced. This embodiment; indicates tlie-con dition of tlie fluid level to remote positions und at diilicult angles, just as before and may be. conveniently viewed, for example from below .the gauge' vand at angles of l5 degrees and less.

l. parallel faced transparent plate 66.

I, or nir while the rays 73 due to their differ- In F ig. 6, 'i have sliownv a transp-arent plate G5 for embodying tlie'i'nvention in a gauge of the type shown in Fig. 5, with a The plate having the desired inclined faces is secured to tbe' late (36 by a' cementitious trunsparentbin er 67 forv otherwise as ,de

In Fig. 7, I have provided-for producing the desired level indication without directing the rays bet'vveeu'tlie critical refraction :ingles 'ofthe transparent niii-terizil of the different luids und Without :in additional filter of selector screen.

In this case thel inner surface of the rear 'transparent plate or iviill 68 is corrugated or divided into tivo groups of generally parallel surfaces-69 and 70 respectively. The

surfaces 7() are covered or otherwisesuitably T bese finish-ed to :make tiiei'n opaque. opaque surfaces TO are positioned to intercept the rays 72 ivliicli penetrate the steam ent refraction by the Water strike the surfaces I69 where the 'vmter is encountered' and are retracted thru tbe plete GSbeing directed therefromat 74 :ind upon a suitable diu-r as desired to give t-lie indication of the 'liquid level Vivitliin the gauge. The filter `for perallelingthe incident rays is indica-ted nl'. 75

and the source of iight is indicated diagrammausi-1y ai 7e. Thev indication in this 4is secured by tli'diierent'indi-ces of refrac;

tion of the diterentiluids and without. theV necessity of Vadditional screens or the like.

In Figs. 8 and 9 the invention is embodied partially embracing tbe tube 78 at 83, 83.

The tube 78 is -o 'en for' vision .between the front margins o the embracing sides 83 of the reflector 82.

In Figs. 10 and 1 1, tlie invention is sli-own as applied to a straight walled. tube 85. The

refiactor 8G may be in tbe forni of a. sleeve or it may be made up of separate refractor parts 87 :is shown in Figyll, suitably secured as by means of iitransparent ccmcntitions `binder 88 upon the outer surface of the tube 85. I In Figs. 12 ,and 13, Vthe single side embodi- BOF ment er Fig. 5 is embodied in :i tube type'.

gauge. The straight, walled tube 89 has secured thereto as by :i suitable ceinent-itious transparent binder 90 the reti-actor 91 on one side- The opposite side of tbetube 89;"

is covered by a steel or other. suitable guard- 92 the surface 93 of which is preferibly un'- olished sind of dark color or otherwise finished so that the rays o .flightpenetrating one of the fluids will' not be reflected vWhere- :is the indication is given by the reflection of the rays from the other fluid. The steel guard 92 surrounding the glass' tube S9 acts 4addition-ally asa reinforcement and a safetydevice in the 'case of breakage and it may be cemented or 'otherwise suitably 'secured to the tube.r l t In Figs. 14 and 15, the invention is again v.embodied in a Atube .type gnu-ge with another i'io reinforcing provision fort-he tube. The tube is indicated at y95 and is einbraced'by a per orated metal sleeve 96 which may be suitably forced iipoiiv the tube and the. refractive strips or members 98 rire secured upon .the vtube over the sleeve .96 :is by suituble'cenien-- vtitioiis transparent material.

The mesh sleeve 9G sleeve 96" i'iiaybe relatively Asmell vso as to not obstruct the visibility. The small size of the reinforcement would not obstruct the visibility' especially if' 'sligl-itly diiusing glas isused.

The perforations in the' reinforcing sleeve 96 give thefsleeve lenough flexibility to expand with the glass end an alloy having the same lie-at expansion cofeflic`ient as glass n could obviously be used.'

Fig. 19 the incident rays 1G()l are drectreinforces und strengthens the tube .95-:i-nd--t'lie 'nics'li of tba A :ed inj-perallelisnl .niteblemeanS-not showmglpon the surfao'es'lOl of the Vglass `and 114 theA at sided glass walls may be .glass v'01E a character to' withstand high presand the likewhilethe -refracting members may he cfa different glass, for example,

'plete 102 the' ang-le of which such-tlmt the 'rays'ar'e totally reflected therefrom at 103:281.

an lengje between the critical refraction angles of the fluids. This produces a. series yec-tion at l'lwhere one fluid is encountered and 'refraction thru the other fluid where it is encountered.` The raised v o's1'' .tion ofthe source of light and the reltively Asteep angle of the incident rays is 4thus avoided. 1

`Viith the rovi-sions of Figs. 4, 6, l0, l2

.one that is more s ired form.

' I claim:

1. The methodl of easily brought to the deindicating the relative i positions of fluids with different eri-tical re- Va.' iiuidy which lcomprises directing incident fraction angles which comprises directing parallel rays of light toward said fin-ids et an angle between the' criticalrefraction angles p f the fluids to produce onl reflected rays Where one fluid is enconntere and only refracted rays thru the other flu-id and conveynig one group of rays .thus produced to the observer.A v

2. The method -of indicating the level 0f a. Huid which comprises essing parallel .rays of Vlight toward said uid at an an le between the critical refraction angle vof t e Huid and the. critical refraction angle of the mediumv above the iuid to produce total freecton of the. rays'above the fluid and total refraction of the rays thruv the iu'd below said' level and conveying one group'of rays, thus produced to the observer.

3. The method o indicating the level of rays of light in parallelism 'u on a. traue parent wall in front of the uid column,

-whic'h wall is constructedfor refrecting said rays at an angle between the critical rerction angle of the iluid and thecritical "refraction angle of .the mediumabove the fluid to produce totl reiection ofthe rays above the fluid level and total. 'refraction Aoft the rays' thru the ilnid, helowasai'd level and conveyingone group of rays thus produced to the observer. v

il: fhenmethodof indicating the relative posxtions' of fluids withdierent critical rereptlon engl-'es which compri-ses directing lnld'ent rays'of 'light in parallelism upon Va transparent Wallin fron-t of the iuids2 which .wall lisconstructed yfor refracting seid rays oigan angle between the critical refraction angles of the fluids to produce onl -reected rays Where` one :l-uid is :.encoimte .endcnly refracted rays thru the' other :fluid .and 60.11- 'jeying' Aone group off the resultant rays -to the observer.

' interposed between said .means und the-:fluid A 5. The method of indctllg the relative I ositons lof i-nids with diierent critical re- Aaction angles which comprises directing incident rays o f light n parallelism u n a transparent Wall in front of the fluids, which wall reconstructed for refracting sald rays et an angle betweenlthe criticalfremction angles o the 'inids to produce onl. reflected rays where one fluid is enconnte and only refracted rays where the other fluid is en countered and diffusing' one' group otra s thus produced to indicate to the observent e; relative positions of said fluids.

6. In combination, a column for fluids4 with different critical refraction angles va.

source of light means for directing parallel i interposed between seid means and the fluid.

column and divided into a plurality of'snraident parallel rays at vsuch an :ingle that said rays will be reieeted -where Aone duid is- .encount-ered vandjreractecl thru the `other 8. In combi-nation, .a column. Ifor iin-ids with dierent criticl refraction angles, a' 'source of light, means .for directing only parallel rays of light from 'seid source' toward seid column and a. transparent Wally column and 'divided intere. plurality of surfaces inclined eten angle to reract all incident perellelA rays at such angle ,that said rays will he reflected where one Enid is encountered and vthe surfaces of said transi arent wall between saidin-clined' surfaces, eing positioned .wholly without the path O seid arallel incident rays. Y 9, n afand level indicator, means for .di-

meting .onl' .parallel rays of light from a 1 y source, an atransparent wall shaped to' refr-act all incident arallel rays-of light transmitted thereto .y said means et an angle 4between the respective c'rtirnl-reracticnangles of the nids Within the Indicator 10. Incombinatiou, -a column vforfilnids 'with di-erent -criticcl reflection angles, a.`

vsoin-.ce of light, means for directing. only parallel 'rays of lightfrom said source toward seid, coiumn, ,and trenspaientwcll n1- terpo'sed between said means and 4the id .column and formed to refr-act 'all incident. l

parallel ht rays-at euch aniangle thatsaid will reflected wher'ehne l'uid is en- 'countered reractedlhru the other -md 1 faces vinclined at .en angle to refract all n- 95 v said combinetion being' arranged to convey the retracted rays tothe observer to indicate .the-level of the fluid. Y

l1. As an article of manufacture a transparent reracting Wall adapted 'for installa'- tion in parallel sur-faced gauges and faces f formed on said 'wall to retract parallel ra 's ingl wall divided into surfaces inclined tojrefract rays of lightl at such an angle that they Will be reflected bzick thru the transparent wall 'where one fluidis encountered and re- I racted thru a fluid having a different cri` tical refracting anffle and lmeans securing said transparent reracting Wall to said first transparent Wall; l

13. In a level indicator, a diffu-ser, for re` loei-ving rays of light for indicating the level of a fluid to be observed, said 'diffuser having oppositely disposed faces, a characteristic finish on said faces on one side of a. predetermined fluid levelpoin'tnnd a ydistinctively different characteristic finish on said faces lon the opposite side of'said point, vsaid -inr ishes assisting to indicate the level of sai-d observed Huid .relative to said point.

14. In a level indicator, -a gauge tube, a

perforated reinforcing sleeve surrounding said tube, and a transparent retreating ineinber securednpon the tube over said re'- mioreing sleeve.

15. In a level indicating.' n 'gauge tube, n.

.the rays th-rouhtrnnspnr-ent. vi-all in front 'oit the -tlriidfolumn, wghc'hfwelI-ijs constructed for retract.-y ng said rays'at n n vmgl-ebetvvee.n the criti-- cal refraction .angle of the-fluid andthe cri- .ti'c'al refraction angle of the .med-im above the duid- :toproduce total reflection of the rays 'above the fluid level and refraction of .the -tlnidbelow said level.

179. The met od'V of determinin the relative positions olf .fluids with eliferent cri tical refraction angles -wlrieh comprises directing incident rays of light in parallelismupon a transparent Wall in front of the fluids, which Wall is constructed for refract said rays 'at an angle between the critical re ractio-n vongles of the fluids .to produce" only reflected ra-ys.whe're one fluid is er1-- countered and only retracted rays through the' other lluid.

In w'itness`-w-hereof, I hereunto subscmbe my name this v9th day of-Jnne, '1927, l

ANDREW CR. LE BAHJLY.

- source ot light, means `for'refractn,,.the ra s. v Y

of light at suc-:li :triangle that they 'will reflected `back wherezone fluid is encountered within the tube and re-racted on thru a fluid having a different critical refraction-angles' anda reinforcing -guard for the tube with the surface of said "guard presented to the light. finished so Athat .the rays .off light penetratingone fluid will not 'be reflected.- L16. The meth-od 'of .determining the relyative positions of fluids with different cri-V tical refracting angl-es which `comprises di,-

resting parallel rays of .light against said luds at .an angle hetweenthe critical ree' fraction angles "of the fluids .produce re- 4lected rays where one fluid is encountered and refracted rays through th'e'other lu'id'.` 17. The method of determining the level 'ofa fluid which .comprises passing rays ofits' light againstsaid fluid at an angle between the cri-tical vrefractio'nl'airgle.of the fluid and the critical .refraction angle Vof* the frnedinm above the fluid to produce total freile'ctioitl` of the rays above the-nid .and refraction of v the rays through the fluid below said level ISL-.The method 'of' .determining vthe :level-f" f of-a lluid Which'compiises directinginoi-- dent raysonllight in .parallelism lupon. a 

